Hi Martin, good luck on your exam!!
Yes, the PMPrepcast tests are much harder than the actual CAPM. If it makes you feel better - I took all 5 PMPrepcast exam simulators in the last month, I failed 4 of them and only passed one by the skin of my teeth. But when I took the CAPM on Monday, I passed with Above Target in all categories. So definitely don't doubt yourself too much. I found that doing poorly on the practice exams did motivate me to study a LOT, which did pay off and which I'm glad I did.
I only had one earned value analysis formula question (or maybe two?). Personally, I memorized the EVA formulas (and also made sure I understood them, not just memorized) so when these came up they weren't hard at all. And the exam has a built in calculator so if you freeze and forget what 4x5 is, you can just use the calculator.
I had 3 questions where I had to draw out a schedule network diagram and calculate the critical path (just addition). I also had one question where I had to calculate the EVM in a decision tree.
There were a lot of questions where I needed to know the ITTOs to be able to answer correctly. I must admit, I did not at all memorize the ITTOs. I reviewed them a lot so I was familiar with them. What I DID memorize (which I'm very glad I did), was the chart with all the processes (with the Process Groups across the top and the Knowledge Areas down the side). I practiced writing out the whole chart from scratch a bunch of times until I could do it quickly from memory. So when the ITTO questions came up, I could quickly close my eyes and imagine where the question was pointing me on that chart, and from there the correct ITTO answer would just make natural sense.
The CAPM had a few questions that asked you to apply your knowledge to a situation, but most questions just asked you to show that you know the terms, ITTOs, can calculate critical path, etc. I also found that PMPrepcast questions throw you off with answers where it *feels* like more than one answer could be correct - with the CAPM, as long as you know the material, it was usually obvious which was the right answer.
I'm sure you'll do great - good luck!